Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark.
Colloids Surf B Biointerfaces. 2011 Jul 1;85(2):373-8. doi: 10.1016/j.colsurfb.2011.03.014. Epub 2011 Mar 23.
The development of nanoparticles has greatly improved the catalytic properties of metals due to the higher surface to volume ratio of smaller particles. The production of nanoparticles is most commonly based on abiotic processes, but in the search for alternative protocols, bacterial cells have been identified as excellent scaffolds of nanoparticle nucleation, and bacteria have been successfully employed to recover and regenerate platinum group metals from industrial waste. We report on the formation of bio-supported palladium (Pd) nanoparticles on the surface of two bacterial species with distinctly different surfaces: the gram positive Staphylococcus sciuri and the gram negative Cupriavidus necator. We investigated how the type of bacterium and the amount of biomass affected the size and catalytic properties of the nanoparticles formed. By increasing the biomass:Pd ratio, we could produce bio-supported Pd nanoparticles smaller than 10nm in diameter, whereas lower biomass:Pd ratios resulted in particles ranging from few to hundreds of nm. The bio-supported Pd nanoparticle catalytic properties were investigated towards the Suzuki-Miyaura cross coupling reaction and hydrogenation reactions. Surprisingly, the smallest nanoparticles obtained at the highest biomass:Pd ratio showed no reactivity towards the test reactions. The lack of reactivity appears to be caused by thiol groups, which poison the catalyst by binding strongly to Pd. Different treatments intended to liberate particles from the biomass, such as burning or rinsing in acetone, did not re-establish their catalytic activity. Sulphur-free biomaterials should therefore be explored as more suitable scaffolds for Pd(0) nanoparticle formation.
由于较小颗粒的更高表面积与体积比，纳米颗粒的发展极大地提高了金属的催化性能。纳米颗粒的生产最常基于非生物过程，但在寻找替代方案的过程中，细菌细胞已被确定为纳米颗粒成核的极好支架，并且已经成功地利用细菌从工业废物中回收和再生铂族金属。我们报告了在两种具有明显不同表面的细菌物种表面上形成的生物支持钯（Pd）纳米颗粒：革兰氏阳性的松鼠葡萄球菌和革兰氏阴性的贪铜菌。我们研究了细菌的类型和生物量如何影响形成的纳米颗粒的大小和催化性能。通过增加生物质：Pd 比，可以生产直径小于 10nm 的生物支持 Pd 纳米颗粒，而较低的生物质：Pd 比则导致颗粒从几纳米到数百纳米不等。生物支持 Pd 纳米颗粒的催化性能针对 Suzuki-Miyaura 交叉偶联反应和氢化反应进行了研究。令人惊讶的是，在最高生物质：Pd 比下获得的最小纳米颗粒对测试反应没有反应性。这种无反应性似乎是由硫醇基团引起的，硫醇基团通过与 Pd 强烈结合而使催化剂中毒。旨在将颗粒从生物量中释放出来的不同处理，例如燃烧或在丙酮中冲洗，并没有恢复它们的催化活性。因此，应该探索不含硫的生物材料作为 Pd(0)纳米颗粒形成的更合适支架。
